High‐frequency coherence functions propagated along ray paths in the inhomogeneous background of a weakly random medium: I—Formulation and evaluation of the second moment

1987 ◽  
Vol 81 (4) ◽  
pp. 925-937 ◽  
Author(s):  
R. Mazar ◽  
L. B. Felsen
Keyword(s):  
High Frequency ◽  
Random Medium ◽  
Second Moment ◽  
Frequency Coherence ◽  
Ray Paths

High-frequency seismic noise as a function of depth

1991 ◽  
Vol 81 (4) ◽  
pp. 1101-1114
Author(s):  
Jerry A. Carter ◽  
Noel Barstow ◽  
Paul W. Pomeroy ◽  
Eric P. Chael ◽  
Patrick J. Leahy
Keyword(s):  
New York ◽  
High Frequency ◽  
Seismic Noise ◽  
Low Frequency ◽  
Time Variability ◽  
Orthogonal Components ◽  
The Difference ◽  
Frequency Coherence ◽  
Cultural Noise ◽  
Natural Wind

Abstract Evidence is presented supporting the view that high-frequency seismic noise decreases with increased depth. Noise amplitudes are higher near the free surface where surface-wave noise, cultural noise, and natural (wind-induced) noise predominate. Data were gathered at a hard-rock site in the northwestern Adirondack lowlands of northern New York. Between 15- and 40-Hz noise levels at this site are more than 10 dB less at 945-m depth than they are at the surface, and from 40 to 100 Hz the difference is more than 20 dB. In addition, time variability of the spectra is shown to be greater at the surface than at either 335- or 945-m depths. Part of the difference between the surface and subsurface noise variability may be related to wind-induced noise. Coherency measurements between orthogonal components of motion show high-frequency seismic noise is more highly organized at the surface than it is at depth. Coherency measurements between the same component of motion at different vertical offsets show a strong low-frequency coherence at least up to 945-m vertical offsets. As the vertical offset decreases, the frequency band of high coherence increases.

Output Gap, Money Growth and Interest Rate in Japan: Evidence from Wavelet Analysis

2018 ◽  
Vol 18 (2) ◽  
pp. 171-184
Author(s):  
Aviral Kumar Tiwari ◽  
Olaolu Richard Olayeni ◽  
Reza Sherafatian-Jahromi ◽  
Olofin Sodik Adejonwo
Keyword(s):  
Interest Rate ◽  
High Frequency ◽  
Money Growth ◽  
High Frequencies ◽  
Time Frequency ◽  
Long Run ◽  
Direction Of Causation ◽  
Cyclical Relationships ◽  
Frequency Coherence ◽  
The Relationship

This article investigated the relationship between output, money and interest rate, using wavelet tools for the period 1972–2017. Application of such tools is helpful in answering particularly two questions: first, what the strength and direction of the causal relationships between money, output and interest rate is, and second, whether the relationship is cyclical or anti-cyclical in nature. Findings from this article show that output and money are highly coherent in low, middle and high frequencies, and coherence increases while controlling for interest rate, with money growth as the leading variable most of the time across frequencies. Output and interest rate are equally highly coherent, mostly at high frequency and some bits of middle frequency; coherence increases with the control for money, and interest rate often times leads the relationship. Also, money and interest rate are coherent at low, middle and high frequencies with interest rate leading the relationship, and controlling the effect of output increases the coherence at some times and decreases at other times. There are observable evidences of both cyclical and anti-cyclical relationships among the variables. Policy decisions should be cautious of shortrun moves in order not to trigger undesired long-run outcomes since no difference is observed in the direction of causation over time–frequency. JEL: C49, E43, E52

scholarly journals Simulated high frequency ray paths considering traveling ionospheric disturbances

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Mariano Fagre ◽  
Bruno S. Zossi ◽  
Jaroslav Chum ◽  
Ana G. Elias
Keyword(s):  
High Frequency ◽  
Ionospheric Disturbances ◽  
Traveling Ionospheric Disturbances ◽  
Ray Paths
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